1. Field of the Invention
The present invention relates to a bag transport and tilt-correction device that corrects tilt of bags within a bag vertical plane during the process of transporting the bags held in a vertical orientation from a bag receiving position to a bag hand-over position.
2. Description of the Related Art
Japanese Patent Application Laid-Open (Kokai) No. 2006-224546, for instance, discloses a rotary-type bag manufacturing device for manufacturing a bag equipped with a spout. This rotary-type bag manufacturing device includes a plurality of bag-holding units provided on the periphery of an intermittently rotating table and, while the table makes one rotation, receives a supply of bags in each of which the top edge part is opened and the shoulder part is cut diagonally, holds the bag horizontally in the bag-holding units, inserts a spout into the shoulder part of each bag, and adheres the spout to the shoulder part, thus manufacturing a bag equipped with a spout. As shown in FIG. 1 of this Japanese Patent Application Laid-Open (Kokai) No. 2006-224546, the bag equipped with a spout manufactured by this device is conveyed to the outside of the device by a discharge conveyer; and discharged bags with spouts are stacked and, as well known, manually supplied in a vertically stacked state into a bag supply magazine of a bag-supplying device or supplied in a state layered spread out in a cascade like fashion in a conveyer magazine-type bag supply device (in a state layered skewed in the vertical direction so that the top bag comes to the front), and then from there, the bags are supplied to, for example, a rotary-type bag packaging apparatus.
In the case of a bag equipped with a diagonal spout, as seen in typical, common bags, both side edges of such bag are gripped by a gripper in the bag packaging apparatus, the bag mouth is opened, and after the bag is filled with the content, the bag mouth is closed and sealed. However, when this kind of bag with a diagonal spout is supplied to the bag packaging apparatus, if the bag is tilted within the plane, it is gripped and suspended by the gripper in a state tilted within the vertical plane. Tilt within the plane of a bag can also occur for bags not equipped with spouts.
When, as described above, a bag gripped by the gripper is tilted, printing (of, for instance, manufacturing date and expiration date) on that bag performed by the bag packaging apparatus is also tilted, and a bag-mouth seal becomes diagonal with respect to the bag's top edge, deteriorating the visual quality of the bag. Also, when the tilt is great, there is the possibility that other problems would occur in other packaging processes performed by the bag packaging apparatus.
Japanese Patent Application Laid-Open (Kokai) No. 2006-240649 discloses a rotary-type bag packaging apparatus; and in this rotary-type bag packaging apparatus, a tilt detection is performed for a bag gripped by a gripper before opening the bag mouth; and if a tilt is detected, that tilt is corrected during the process of opening the bag mouth. Typically, the tilt correction is performed so that after the bag surface is suction-held by a vacuum-suction disk, the gripper is temporarily opened, the vacuum-suction disk is rotated and the bag is rotated by the amount of the tilt; and after the tilt of the bag is corrected, the gripper is again closed to grip the bag. In this method, since the bag is not tilted after the process of opening the bag mouth, the bag-mouth seal, for instance, will not be diagonal with respect to the bag top edge. However, the printing process is typically performed before the process of opening the bag mouth or before tilt-correction, it is accordingly not possible to prevent inclination in the printing. Also, in the method of Japanese Patent Application Laid-Open (Kokai) No. 2006-240649, it is necessary to temporarily open and close the gripper during the process of opening the bag mouth; as a result, the gripper mechanism is complex, extra time is required for opening and closing of the gripper, and thus it has a problem that the productivity of the bag packaging apparatus is low.